Image forming apparatus, method of forming gradation patch, and evaluation chart of the image forming apparatus

Abstract

An image forming apparatus includes an image forming device and circuitry. The image forming device is configured to form an image on a sheet. The circuitry is configured to acquire density information from image information of the image formed on the sheet, determine a width of each of a plurality of gradation patches to be formed in a conveyance direction of the sheet based on the density information, and cause the image forming device to form the plurality of gradation patches having different widths from each other in the conveyance direction of the sheet, in a margin area of the sheet.

What is claimed is: 
     
         1 . An image forming apparatus comprising:
 an image forming device configured to form an image on a sheet; and   circuitry configured to:   acquire density information from image information of the image formed on the sheet;   determine a width of each of a plurality of gradation patches to be formed in a conveyance direction of the sheet based on the density information; and   cause the image forming device to form the plurality of gradation patches having different widths from each other in the conveyance direction of the sheet, in a margin area of the sheet.   
     
     
         2 . The image forming apparatus according to  claim 1 ,
 wherein the plurality of gradation patches includes first gradation patches each including a priority gradation and second gradation patches each including a non-priority gradation that is not the priority gradation, and   wherein a width of each of the first gradation patches is greater than a width of each the second gradation patches.   
     
     
         3 . The image forming apparatus according to  claim 2 ,
 wherein the circuitry is configured to define the priority gradation based on the image formed on the sheet and a width of the margin area on the sheet.   
     
     
         4 . The image forming apparatus according to  claim 3 ,
 wherein print data on the gradation patches formed per a given number of sheets include data on the image formed on the sheet and the width of the margin area on the sheet.   
     
     
         5 . The image forming apparatus according to  claim 1 ,
 wherein the plurality of gradation patches includes first gradation patches of a priority color and second gradation patches of a non-priority color that is not the priority color,   wherein a difference in gradations of the first gradation patches is smaller than a difference in gradations of the second gradation patches, and   wherein a number of the first gradation patches is greater than a number of the second gradation patches.   
     
     
         6 . The image forming apparatus according to  claim 1 ,
 wherein the plurality of gradation patches includes first gradation patches of a priority color and second gradation patches of a non-priority color that is not the priority color, and   wherein the circuitry is configured not to form the second gradation patches of the non-priority color.   
     
     
         7 . The image forming apparatus according to  claim 1 ,
 wherein adjacent gradation patches in adjacent two different colors of gradation patches of the plurality of gradation patches have a smaller density difference in color than non-adjacent gradation patches of a same color in the adjacent two different colors of gradation patches.   
     
     
         8 . The image forming apparatus according to  claim 1 ,
 wherein the circuitry is configured to:
 acquire the density information from image information of an image to be formed on another sheet that is conveyed after the sheet, and 
 cause the image forming device to form the plurality of gradation patches on the sheet based on the density information. 
   
     
     
         9 . The image forming apparatus according to  claim 8 ,
 wherein the circuitry is configured to cause the image forming device to form no gradation patch on the sheet when there is no image to be formed on said another sheet.   
     
     
         10 . The image forming apparatus according to  claim 1 , further comprising:
 a reader configured to read the plurality of gradation patches on the sheet,   wherein the circuitry is configured to calculate a color correction value based on a reading result of the reader.   
     
     
         11 . A method of forming a plurality of gradation patches, the method comprising:
 acquiring density information from image information of an image formed on a sheet;   determining a width of each of the plurality of gradation patches to be formed in a conveyance direction of a sheet, based on the density information; and   forming the plurality of gradation patches having different widths from each other in the conveyance direction of the sheet, in a margin area of the sheet.   
     
     
         12 . An evaluation chart for an image forming apparatus, the evaluation chart comprising:
 a sheet;   an image formed in an image area on the sheet by the image forming apparatus; and   a plurality of gradation patches formed in an area outside the image area and having widths different from each other in a conveyance direction of the sheet.